Writing instrument



FIG. 1 is a perspective illustration of a writing instrument embodying our new design;

FIG. 2 is a bottom plan view;

FIG. 3 is a front elevational view;

FIG. 4 is a right side elevational view;

FIG. 5 is a rear elevational view; and,

FIG. 6 is a top plan view. 

The ornamental design for a writing instrument, as shown. 